Emission standards for vehicles equipped with a diesel engine may dictate acceptable levels of NOx. To accomplish such reduction of NOx emissions, vehicles may be equipped with an SCR system that uses a fluid, such as diesel exhaust fluid (DEF) (e.g., urea), as the reductant. The DEF fluid may be carried in an onboard tank that requires periodic refilling. Further, in some systems, the DEF refill port may be located in direct proximity to the refill port for fuel, such as diesel fuel.
The inventors of the present application have recognized a problem in such previous solutions, in that it may be possible for a customer to mistakenly dispense DEF into the fuel tank. Adding DEF to the fuel tank could result in permanent degradation to the low and high pressure fuel system and/or degradation to the base engine due to the corrosive nature of some reductant fluids, such as urea.
Accordingly, in one example, some of the above issues may be addressed by a system comprising a reductant storage system including a reductant reservoir for holding a water-based reductant, and an exhaust delivery system to deliver the water-based reductant to the exhaust. The system further comprises a fuel system including a fuel tank, a water separator for separating water-based fluid from fuel in the fuel tank, and a separation reservoir to collect separated water-based fluid. The system further comprises a controller including instructions to indicate mis-filling of the water-based reductant into the fuel tank in response to an amount of water-based fluid in the separation reservoir.
In this way, since reductant is typically water-based, the fuel filter may react to remove the reductant from the diesel fuel and the reservoir would fill rapidly. Thus, detecting sufficient change in the reservoir after a fuel refill event indicates that contamination may have occurred (e.g., diesel fuel has been contaminated by the addition of reductant). The system can then notify the customer to take the appropriate action to prevent significant degradation to the fuel system and engine to reduce costly repairs. Further, since such detection can be implemented via instructions for a controller, any additional hardware inside the fuel system for detecting reductant contamination may be optionally eliminated.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.